It's not so much the # of gangs, but the cubic inches in the box. The number of cables and the size of the item to be mounted each has a value when added up, it can't be bigger than the volume of the box.

If it is a non-metallic box it will have the cubit inches stamped in the back of the box. Do the calculation of the conductors and devices going into the box to see if it is overfilled.
See Table 310.16(B) and Section 310.16 for more information. If you don’t have access to a code book let me know and I will copy and paste them here.